Speed governor



De- 9, 1952 w. E. LEIBING 2,629,821

SPEED 'GOVERNOR Filed April 14, 1947 3 Sheets-Sheet l attorneys.

w. E. LEIBING SPEED GovERN'oP.

Dec. 9, 1952 Filed April 14, 1947 3 Sheets-Sheet 2 Mam/vf.' H5/N6,

Snventol;

DEC- 9, 1952 w. E. LEIBING 2,620,821

sPEoGovERNoR Filed April 14. 194'? 3 Sheets-Sheet 3 a l Jfz .3.

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OPI/V Gttornegs.

Patented Dec. 9, 1952 UITED STATES @A'i' Claims.

This invention relates to speed governors for internal combustionengines and is directed to improvements for controlling the position ofthe throttle valve for limiting the maximum speed of the engine.

The principal object of this invention is to provide an improved form ofspeed governor for an internal combustion engine which acts to maintainwithin close limits a preselected maximum engine speed irrespective ofthe load imposed upon the engine.

Another object is to provide an improved form of engine speed governorwhich is economical to manufacture and which employs only a standardform of spring of conventional design and yet which is capable ofgoverning the maximum engine speed within close limits.

Another object is to provide such a governor in which the maximum enginespeed may be selected as desired, without changing springs.

Another object is to provide a speed governor in which friction lag issubstantially overcome by opposed diaphragme, one connected directly toa source of vacuum pressure and the other connected through a valvecontrolled oriiice to a source of variable vacuum pressure which variesin accordance with the position of the throttle valve.

Another object is to provide a governor of this type which employs checkvalves to protect the diaphragms against rupture in the event of backredownstream from the throttle valve.

A further object is to provide an engine speed governor which overcomesthe tendency of prior art governors to lock up during a period ofdeceleration when the engine is being driven from the momentum of itsnormally driven load.

Other objects and advantages will appear hereinafter.

In the drawings:

Figure 1 is a top plan view of a speed governor for an internalcombustion engine and illustrating a preferred embodiment of myinvention.

Figure 2 is a sectional elevation taken substantially on the lines 2 2as shown in Figure 1.

Figure 3 is a sectional elevation taken substantially on the lines 3 3as shown in Figure 1.

Figure 4 is a sectional elevation taken substantially on the lines li-ias shown in Figure 2.

Figure 5 is a sectional plan View taken on line 5 5 as shown in Figure3, and illustrating on an enlarged scale a plug element employed inconnection with my invention.

Figure 6 is a schematic sectional View illustrating the action of apreferred form of diaphragm with respect to its enclosure.

Figure 7 is a graph illustrating a typical relationship between angularposition of the throttle valve with relation to the vacuum pressure inthe engine manifold, the engine speed remaining constant.

Figure 8 is a graph illustrating a typical relationship between engineR. P. M. and ft.lbs. of torque output and illustrating the action of agovernor embodying my invention in controlling the maximum engine speedat any one of a plurality of preselected speeds.

Referring to the drawings, the graph shown in Figure 7 includes curve Awhich represents a relatively high governed speed, for example, 3,000 R.P. M. and the curve B` represents a relatively low governed speed, forexample, 1,200 R. P. M.

Considering first curve A, when the throttle valve of the engine isfully open and the load on the engine is suiilciently great to limit thespeed to 3,000 R. P. M., the vacuum pressure in the engine manifold isabout 3 inches of mercury. As the load on the engine is decreased, thethrottle valve must be turned toward closed position in order tomaintain the engine speed constant, and, therefore, when the throttlehas turned approximately degrees from open position, the Vacuum pressurein the manifold is increased to almost G inches of mercury. Similarly,as the load is released from the engine and the throttle valve turnedfurther toward closed position in order to maintain the engine speedconstant, manifold vacuum pressure would reach about l1 inches ofmercury when the throttle valve had been rotated about degrees, and whenthe entire load has been released the vacuum pressure would reach about16 inches of mercury and the throttle valve would have been rotatedabout 72 degrees.

. Curve B represents the vacuum curve of the same governor when set at alower speed, for example, 1,200 R. P. M. With full engine load and wipeopen throttle, the manifold vacuum pressure would be less than one-halfinch of mercury. As the load is released and the throttle valve turnedto maintain the engine speed constant, the manifold vacuum pressurewould reach about 4 inches of mercury after 35 degrees of rotation ofthe valve and would reach about 19 inches of mercury when the valve hadrotated 77 degrees and the load on the engine completely released.

The purpose of the engine speed governor is to control the angularmovement of the throttle valve exactly as shown by curves A and Bdepending on the vacuum pressures existing in the engine manifold. Ifthis is done, the engine will maintain a substantially constant maximumspeed regardless of a varying load.

In order to limit the maximum opening of the throttle and thus limit themaximum engine speed, the manifold vacuum is applied to a diaphragm orpiston, but in such event a force opposing the movement of the pistonmust be applied. This force must be a varying one and therefore thestraight line characteristics of a tension or compression spring are notsuitable. In other words, the curves A and B are not straight lines,and, therefore, a particular spring which is sufficiently weak toapproximate the lower ends of the curves A and B near the open positionof the throttle are entirely too weak for the intermediate and finalranges of the curves toward the closed position of the throttle. Inprior art governors, attempts have been made to provide springs whichhave a varying spring rate to correspond with the shape of the curves Aand B, but the difficulty of providing such springs in practice and ofadjusting the springs for different governed speeds has resulted yinconstructions which were held too costly or too delicate for theintended service. From this discussion it will be understood that ahighly desirable feature cf my invention is the provision of a governorwhich will automatically position the throttle valve at the correctangular position in response to increasing vacuum pressure in themanifold so that the maximum engine speed is maintained substantiallyconstant.

The'structure which I provide for accomplishing the purposes set outabove includes a carburetor barrel I having an upper flange II forattachment to the flange of a carburetor of the down draft type (notshown), and the lower fiange I-2 for attachment to the engine intakemanifold (not shown). lThe barrel I9 is provided with a central bore orfiow passage I3 in which is mounted a conventional form of throttlevalve assembly generally designated I4. This assembly includes a pivotshaft I5 rotatably supported in bearings IS extending across the barreland having a throttle disk valve Il fixed thereto. A clutch mechanism I8providing an angular lostmotion connection connects one end of the pivotshaft I5v with the actuating stub shaft I9. An actuator crank 20 isfixed to the stub shaft I9 by means of the nut QI, and an arm 22 fixedto the barrel IB prevents disengagement of the clutchV mechanism I8. Acrank 23 fixed on the other end of the pivot shaft I5 is pivotallyconnected to a control bar 24 by means of the pivot pin 25. Thearrangement of parts so far described is such that angular movement ofthe control crank 29 serves to turn the pivot shaft I5 and throttle diskI'I within the fiow passage I3 and transverse movement of the controlbar 24 effects the same result.

The control bar 24 is mounted within a case 26 attached to the barrel I0as by screws 26a and provided with a cover 2'! attached by means of thescrew elements 28. At one end of the case is the primary diaphragmhousing 22 which includes the bell portion 30 on the case 26 and thecooperating extension 3l. A fiexible annular diaphragm 32 is clamped inposition between the bell 30 and extension 3l by means of the screwfasteners 33 and defines a primary diaphragm chamber 34 within theextension 3I. A pair of non-resilient washer elements 35 are mountedcentrally on opposite sides of the diaphragm 32 and provide the means bywhich Inotion of the diaphragm is transmitted to the control bar 24. AcleVis 36 is attached to the washers 35 and is pivotally connected tothe control bar 24. Clevis 33 extends through the washers 35 and isprovided with a head portion 35 which acts as a guide to receive one endof the compression spring 3'1. The other end of this spring is carriedon the fitting 38 which is adjustably positioned with respect to theextension 3| by means of the adjusting screw 39 and the lock nut 4G.

A passageway 4I is formed in the case 26 and communicates at one end 42with the flow passage I3 at a point below the throttle valve assemblyI4, and communicates at the other end with the interior of the extension3i by way of the check valve 43 and passageway 44. A spring 45 normallymaintains the valve 43 in closed position against a valve seat 46. Fromthe above description, it will be understood that vacuum pressureexisting within the flow passage I3 below the throttle valve assembly I4is connected to the primary vacuum chamber 34 by way of the openingpassage 4I, check valve 43 and passage 44.

The diaphragm 32 is provided with an annular rib 4'! which is adapted tocontact a generated surface or surface of revolution 43 provided withinthe extension 3I and adjacent the outer part of the movable portion ofthe diaphragm 32. Reference to Figure 6 shows the effect of thecooperation between the rib 41 and the surface 43 in reducing theeffective area of the diaphragm within the chamber 34 as the centralportion of the diaphragm moves toward the chamber. The three positionsshown schematically in Figure 6 illustrate the diaphragm in its fullyeffective position A, an intermediate position B in which its effectivearea has been substantially reduced by contact between the rib and thegenerated surface, and the position C in which the effective area of thediaphragm has been reduced to a minimum. A feature of this constructionis that as the vacuum pressure within the chamber 34 increases, that isto say, as the absolute pressure decreases, the atmospheric pressure onthe exposed side of the diaphragm within the space 49 moves the washers36 toward the right, as viewed in Figures 2 and 6, but the extent ofmovement falls off with increasing vacuum pressure rather than moving asa straight line function, assuming the spring 3l to have a constantspring rate.

At the end of the case 26 opposite from the bell portion 39, anenlargement 5B is provided and a cap 5I is adapted to cooperate with theenlargement to clamp the secondary diaphragm 52 therebetween. The cap 5Iis held in position by means of the screw elements 53. Centralnon-resilient washers 54 connect the central portion of the diaphragmwith a link 24h which, in turn, engages the longitudinal slot 24a in thecontrol bar 24. The secondary chamber 55 defined between the iiexiblediaphragm 52 and the cap 5I is connected to a variable source of vacuumpressure which will now be described.

A plug element 55 is mounted in the wall of the barrel IZ! and providedwith a port 5T of any preferred or desirable shape or design. As shownin the drawings, this port is formed as a slot in the plug 56 extendingin a direction parallel to the direction of fiow through the passage I3.It is recognized that this port may take any one of several differentshapes or designs, and the slot 51 is shown for illustrative purposesonly. A passage 58 in the plug 56 communicates with a metering orice 59which connects with the passage 60. Passage 60 extends into the case 26to the check Valve 6I which is held against its seat 52 by means of thespring 63. The check valve 6l is in communication with the secondarychamber 55 by Way of the passage 54. An opening 65 is provided in thewall of the barrel I0 at a point upstream from the location of the port51 and upstream from the closed position of the throttle valve disk I1.The opening 65 communicates with the passage 60 and an adjustable needlevalve 65 is provided to restrict this communication. The position of theslot 51 is such that the edge 31 of the throttle valve disk I1 passesclosely adjacent thereto when it moves from its closed position towardopen position.

It will be understood that the pressure within the flow passage I3 abovethe throttle disk I1 is substantially atmospheric pressure, whereas thepressure existing within the iiow passage I3 below the throttle disk I1corresponds to the vacuum pressure in the inlet manifold. Accordingly,as the edge 51 of the disk moves about its Divot shaft axis towardopening position, the upper end of the slot 51 is gradually exposed toatmospheric pressure and the further the disk I1 pivots toward openposition, the greater proportion of the length of the slot 51 issubjected to atmospheric pressure rather than vacuum pressure in theinlet manifold.

A small vent passage is provided for each of the vacuum pressurechambers 34 and 55 in order to permit absolute pressure to build up inthe chambers when the vacuum pressure transmitted through the inletpassageways 44 and 64, respectively, falls oi. As shown in the drawings,such Vent openings may be positioned in the diaphragm assembly and maytake the form of a small drilled hole 68 extending through the washers35 and diaphragm 32.

In a similar manner, a bleed port 69 may be provided in the washers 54and diaphragm 52 to enable the chamber 55 to return toward atmosphericpressure when the check valve 6| is closed. If desired, this bleed port69 may be formed by drilling a small hole, for example, 0.040 inch indiameter and then placing a wire of 0.038 inch diameter in the hole. Theleakage occurring through this bleed port 69 is therefore so small thatit has substantially no effect when the inlet passageway 44 is subjectedto vacuum pressure, but will permit the absolute pressure within thechamber 34 to build up by leakage from the atmosphere when the checkvalve 43 is closed.

The check valve 43 acts to protect the diaphragm 32 against ruptureshould an explosion occur within the flow pasage I3 and the rather heavypressure therefrom be transmitted through the passageways 4I and 34. Theexplosion pressure due to this spit-back is thus prevented from damagingthe iiexible diaphragm 32. The check valve El protect-s the diaphragm 52in the same manner, but, in addition, serves another very importantfunction as Will be understood from the following detailed descriptionof the operation of this device.

Assuming that the engine on which the barrel I0 is mounted is driving aloaded truck along a level highway with the engine turning at fullgoverned speed, for example, 3,000 R. P. M. Assuming that the truckbegins to climb a hill, the initial position of the throttle disk I1 maybe adjacent its fully closed position with the edge 61 near the upperend of the slot 51. Under such conditions, the vacuum pressure existingin the fiow passage I3 below the throttle valve assembly I4 isrelatively high, and may correspond to the point X, shown on curve A inFigure 7, and may amount to about 15 inches of mercury, the throttlevalve being positioned degrees from full open position.

As the truck begins to climb the hill, a slight additional load isapplied to the engine and it immediately tends to slow down, and, hence,the vacuum pressure in the manifold falls oil' to a lower gure, forexample, 141A inches. The vacuum pressure within the primary vacuumchamber 34 also falls to |41@ inches. If the secondary vacuum chamber 55were also in direct connection with the engine manifold, the vacuumpressure would also fall olfI in this chamber, but, immediately, theabsolute pressure is higher on the right hand side of the ball check 6|,as shown in Figure 2. It closes and retains momentarily the vacuumpressure within the chamber 55 that it formerly had. If the vacuumchamber 55 were fully sealed and the ball check 6I fully closed, thevacuum pressure within the chamber 55 could never be dispersed once ithad been created, but the very slow leak through the bleed port 69allows atmospheric air to enter the chamber 55 so that after a veryshort interval of time the chamber 55 again reflects the vacuum pressureexisting on the right hand side of the ball check 6I. Accordingly, asthe engine first begins to slow down as the truck begins to climb thehill, there would be a vacuum pressure of about 141/4 inches of mercuryin the manifold and in the primary vacuum pressure chamber 34, but,momentarily, there would still be the same vacuum pressure in thechamber 55 that had existed when the truck was operating on the levelhighway.

At this moment, there are two forces acting to open the throttle valvedisk I1, the spring 31 and the vacuum pressure in the chamber 55. Theseforces are opposed by the vacuum pressure in the chamber 34 acting onthe diaphragm 32, but since the latter vacuum pressure has decreasedslightly, the assembly including the washers 35 and 54 and the link 24hand control member 24 move toward the left, as viewed in Figure 2,thereby turning the throttle valve disk I1 in a counterclockwisedirection toward open position. A succession of such cycles occurs asthe grade increases, and as additional load is applied to the engine. Ineach of these cycles, the throttle valve disk moves toward open positionfurther until the lower edge 61 of the disk I1 passes below the loweredge of the slot 51 at which point the action of the vacuum chamber 55ceases. 'Ihe link 24h then moves within the slot 22a and no longercontributes toward movement of the control member 24 toward the left, asviewed in Figure 2.

During the loading of the engine so far described, the manifold vacuumpressure has decreased along the curve A, as shown in Figure '1, untilit reaches a point, for example, where the throttle valve angularposition corresponds to 50 degrees. At this point, the diaphragm 32 isstill in the position coresponding to C, as shown in Figure 6, and asthe vacuum pressure within the primary vacuum chamber 34 continues tofall, the diaphragm 32 moves from the position C toward the position Bthereby increasing its effective area by reason of the cooperationbetween the annular rib 32 and the generated surface 53.

Accordingly, the rate of change of force acting on the control member 2dis in a straight line function with the absolute pressure existing inthe chamber 34 since the eifective area of the diaphragm 32 varies withthe movement of the member 2. As the load on the engine continues toincrease, the vacuum pressure within the chamber 34 continues todecrease and the diaphragm 32 moves from the position B, shown in Figure6, toward the fully extended position A, at which time the full area ofthe diaphragm 32 is effective. This position A may correspond to anangular position of the throttle disk l1 of about degrees, as shown inthe chart in Figure 7. Further loading of the engine decreases thevacuum pressure in the manifold still further, but the action of thegovernor is now a straight line function with the vacuum pressure sinceonly the spring 3l opposes the vacuum pressure within the chamber 34. Asexplained above, the spring 3l has a constant spring rate.

To summarize, the action of the governor as the engine load increaseswith the engine operating at full governed speed occurs in three steps.The first includes the operation of the secondary vacuum pressurechamber in assisting the spring 3'! to oppose movement of the diaphragm32. rlhe second phase comes into play with the cooperation of the rib 41and generated surface A8 in changing the effective area of the diaphragm32. The third phase utilizes only the straight line resistance of thecompression spring 3?.

The effect of the action of this governor upon the engine speed may bedemonstrated by reference to Figure 8. Assuming the truck to betraveling on a level highway and accelerating toward full governedspeed, and assuming that the governor is set for 1,200 R. P. M. thethrottle lever, not shown, is moved to full position by the truckoperator and the engine speed increases toward 1,200 R. P. M. When thespeed reaches about 1,150 R. P. M., the manifold vacuum pressure buildsup to the point where the diaphragm S2 moves against the action of thecompression spring 37 and moves the throttle disk I1 and toward closedposition. The lost motion connection provided by the clutch I8 thusallows the governor to close the throttle valve assembly lll even thoughthe throttle lever, not

shown, remains at its fully advanced position.

As the engine speed continues to increase, the ft.-lbs. of torque outputdrops ofi rapidly along the solid line A because the throttle valve isbeing moved towards closed position. When the load on the engine isreapplied, the dashed line A represents the relationship between engineR. P. M. and ft.-lbs. of torque delivered. If the governor could be madeabsolutely frictionless, the loading and unloading lines would be exactduplicates. Whenever the load is being released, the conditions alongthe solid will be attained, but when the load is rst released a littleand then immediately reapplied the hesitation of moving from one line toanother always appears.

Accordingly, it will be understood that if the action of the governorcan aways occur too far in one direction so that it must always recoverin the other direction, we may attain a substantially frictionlessgovernor insofar as its operation is concerned. The importance of theauxiliary vacuum chamber 55 together with its ball check El and theresulting delayed action is therefore readily appreciated. Thus, thegovernor is always allowed to position itself on the solid line, forwhenever a load is applied to the engine, the preponderance of forcesacting to open the throttle valve assembly a little too far and theimmediate recovery from this condition again takes place on the solidline.

The curves B and C represent similar action of the governor when set forgoverned speeds of 2,000 and 3,000 R. P. M. respectively.

It will be noted that the diaphragm 52 is considerably smaller indiameter than the diaphragm 32 and is therefore not capable of the sameamount of motion but rather about one-half of said motion. Accordingly,the slot 24a is provided near the end of the bar 24 to allow the bar 24to move throughout the full range provided by the diaphragm 32.

Adjustment provided by the needle valve 6B is important since, inconnection with the adjusting screw S for the spring 37, it enables thegovernor to be set for any desired governed speed of the engine. Theserelatively simple and accessible adjusting members may be turned to setthe governor to hold the engine speed at any desired maximum, such as,for example, 1,200 R. P. M., 2,000 R. P. M., or 3,000 R. P. M., and thesame spring 3! may be used for all three governed speeds.

A peculiar condition has been observed during eceleration, at which timethe truck is driving the engine and under which condition the vacuumpressure in the flow passage I3 may sometimes rise as high as 26 inchesof mercury causing some governors to lock the throttle valve assembly I4in fully closed position and making it practically impossible to openthe throttle valve assembly I4 until speeds far below the desiredgoverned speed have been reached. No such difficulty is present in theconstruction embodying my invention since the secondary vacuum chamber55 is exposed to the vacuum pressure within the manifold. The majorportion of the slot 51 is exposed to the high vacuum pressure, and hencethe control member 24 is moved toward the left, as viewed in Figure 2,and hence no tendency whatever exists to lock up even against vacuumpressures as high as 26 inches of mercury.

Having fully described my invention, it is to be understood that I donot wish to be limited to the details herein set forth, but my inventionis of the full scope of the appended claims.

I claim:

1. In a speed governor for an internal combustion engine, thecombination of a throttle valve assembly for controlling flow ofcombustible mixture through a flow passage, said assembly including athrottle valve disk pivotally mounted within the fiow passage, vacuumpressure responsive means, said means including a pair of opposed vacuumpressure chambers each having a movable element operatively associatedwith the throttle valve disk and adapted to limit the extent of pivotalmovement thereof, port means in the v/all of the flow passage adjacentan edge of the disk when in fully closed position and downstreamtherefrom, means providing a passageway between the port means and oneof said pressure chambers, and passage means connecting the otherpressure chamber' with the dow passage downstream from the throttlevalve assembly.

2. In a speed governor for an internal combustion engine, thecombination of a throttle valve assembly for controlling flow ofcombustible mixture through a ow passage, said assembly including athrottle valve disk pivotally mounted within the flow passage, vacuumpressure responsive means including opposed flexible diaphragmsoperatively associated with the throttle valve disk and adapted to limitthe extent of pivotal movement thereof, port means in the wall of theflow passage adjacent an edge of the disk when in fully closed positionand downstream therefrom. means providing a passageway between the portmeans and one of said flexible diaphragms, and passage means connectingthe other flexible diaphragm with the flow passage downstream from thethrottle valve assembly.

3. In a speed governor for an internal combustion engine, thecombination of a throttle valve assembly for controlling flow ofcombustible mixture through a flow passage, said assembly including athrottle valve disk pivotally mounted within the flow passage, vacuumpressure responsive means, said means including a pair of opposed vacuumpressure chambers each having a diaphragm operatively associated withthe throttle valve disk and] adapted to limit th-e extent of pivotalmovement thereof, port means in the wall of the flow passage adjacent anedge of the disk when in fully closed position and downstream therefrom,means providing a first passageway between the port means and one ofsaid flexible diaphragms, means providing a second passageway connectingthe other flexible diaphragm with the flow passage downstream from thethrottle valve assembly, a check valve in each passageway, and arestricted opening associated with each vacuum pressure chamber actingtobleed each respective chamber to atmosphere.

4. In a vacuum responsive speed governor for an internal combustionengine having a throttle Valve disk pivotally mounted within a flowpassage for combustible mixture; the combination thereof: vacuumpressure responsive means including a pair of opposed vacuum pressurechambers each provided with a movable element, said elements beingoperatively associated with the throttle valve disk and adapted to limitthe extent of pivotal movement thereof, resilient means associated withone of said vacuum pressure chambers adapted to oppose movement of itsrespective element, port means in the wall of the ow passage adjacent anedge of the disk when in fully closed position and down streamtherefrom, means providing a passageway between the port means and theother of said pressure chambers, a check valve in said passageway, and arestricted opening associated with each va-cuum chamber acting to bleedeach respective chamber to atmosphere.

5. In a vacuum responsive speed governor for an internal combustionengine having a throttle valve disk pivotally mounted within a flowpassage for combustible mixture; the combination thereof: vacuumpressure responsive means, said means including a primary vacuum chamberand a secondary vacuum chamber acting in opposition thereto, a movableelement associated with each of said chambers adapted to limit theextent of pivotal movement of the throttle valve disk, means forming apassageway connecting the primary vacuum chamber with the flow passagedown stream from the throttle valve assembly, port means in the wall ofthe flow passage adljacent the edge of the disk when in fully closedposition and down stream therefrom, passage means adapted to establishcommunication between the port means and the secondary vacuum chamberwhereby the force exerted by the element associated with the secondaryvacuum chamber increases as the throttle valve disk approaches itsclosed position, and a check valve associated with said passage means.

WILLIAM E. LE'IBING.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 945,992 Stevens Jan. 11, 19101,579,536 Hodgson Apr. 6, 1926 1,944,638 Englestrom et al. Jan. 23, 19342,196,498 Jennings Apr. 9, 1940 2,269,496 Vanderpoel et al. Jan. 13,1942 2,408,161 Darnell Sept. 24, 1946 2,409,070 Ruby Oct. 8, 19462,424,836 Mallory July 29, 1947 2,482,291 Rush Sept. 20, 1949 2,514,388Gilmore July 11, 1950 FOREIGN PATENTS Number Country Date 21,363 GreatBritain Oct. 20, 1905

